What’s the latest haze situation in Singapore?

SINGAPORE – The haze situation in Singapore has worsened over the past week, with the one-hour PM2.5 in the west breaching “very high” levels in the afternoon of Oct 14.

Similarly, the Pollutant Standards Index (PSI) – a 24-hour rolling average of six key air pollutants including PM2.5 – entered the “very unhealthy” range at 9pm that day in the west.

For those who want a quick check on the latest haze situation, The Straits Times has created a widget for easy reference. The left tab shows in real time the 24-hour PSI readings across five regions in Singapore: north, south, east, west and central. The tab on the right provides the PM2.5 figures for the same five regions.

During hazy periods, the one-hour PM2.5 – an indicator of fine micro-pollutants in the air – is what people should be watching because it points to current air quality. PM2.5 levels should be checked immediately before outdoor activities such as going for a jog.

PM2.5 is the dominant pollutant during periods of transboundary haze, and has the most influence over the 24-hour PSI readings.

The 24-hour PSI is computed based on the daily average concentration of six pollutants, including PM2.5, sulphur dioxide, carbon monoxide and ozone. It is an index to provide easily understandable information about daily levels of air quality.

Fuller details on the differences between PSI and PM2.5 can be found in this ST explainer.

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